UC3842G-S08-R [UTC]
HIGH PERFORMANCE CURRENT MODE CONTROLLER; 高性能电流模式控制器
| 型号： | UC3842G-S08-R |
| 厂家： | 
Unisonic Technologies |
| 描述： | HIGH PERFORMANCE CURRENT MODE CONTROLLER |
| 文件： | 总8页 (文件大小：157K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UNISONIC TECHNOLOGIES CO., LTD
UC3842G
LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE
CURRENT MODE CONTROLLER
■
DESCRIPTION
The UTC UC3842G of high performance current mode
controller is specifically designed for off-line and DC-to-DC converter
applications offering the designer a cost effective solution with
minimal external components. This integrated circuit features
approximately 300µA start up current, a precision reference trimmed
the error amplifier input. Also included are protective features
consisting of input and reference undervoltage lockouts each with
hysteresis, cycle-by-cycle current limiting, and so on.
■
FEATURES
* Low startup and operating current
* User defined switching frequency(Norm is 52kHz)
* Power-saving mode for low power
*Pb-free plating product number:
UC3842GL
* Under voltage lockout with hysteresis
* Over voltage protection
* Latching PWM for Cycle-By-Cycle current limiting
* Internally trimmed reference with undervoltage lockout
ORDERING INFORMATION
Ordering Number
Package
Packing
Normal
Lead Free Plating
UC3842GL-D08-T
UC3842GL-S08-R
UC3842GL-S08-T
UC3842G-D08-T
UC3842G-S08-R
UC3842G-S08-T
DIP-8
SOP-8
SOP-8
Tube
Tape Reel
Tube
UC3842GL-D08-T
(1)Packing Type
(2)Package Type
(3)Lead Plating
(1) T: Tube, R: Tape Reel
(2) D08: DIP-8, S08: SOP-8
(3) L: Lead Free Plating, Blank: Pb/Sn
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Copyright © 2007 Unisonic Technologies Co., Ltd
QW-R103-036.A
UC3842G
LINEAR INTEGRATED CIRCUIT
PIN CONFIGURATION
COMP
1
8 VREF
VCC
FB 2
7
6
3
OUT
CS
CT
4
5
GND
■
PIN DESCRIPTION
PIN NO.
PIN NAME
COMP
FB
I/O
Function
1
2
3
4
5
6
7
8
O
I
This pin is error amplifier output
The error amplifier inverting input
Current sense input
CS
I
CT
I
The capacitor controlling switch frequency
Ground
GND
OUT
VCC
O
O
Output to the gate of external power MOS
Supply voltage
VREF
Inter 5V reference voltage output
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UC3842G
LINEAR INTEGRATED CIRCUIT
■
BLOCK DIAGRAM
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UC3842G
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (Ta＝25°C)
PARAMETER
SYMBOL
VCC
RATINGS
30
UNIT
V
Supply Voltage (Low Impedance Source)
Supply Voltage (ICC<30mA)
Output Current (Peak)
VCC
Self Limiting
±1
V
IO(PEAK)
A
Output Energy (Capacity load)
Junction Temperature
5
µJ
°C
°C
°C
TJ
+150
Operating Temperature
TOPR
TSTG
-40 ~ +125
-65 ~ +150
Storage Temperature
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
ELECTRICAL CHARACTERISTICS
(0°C≤Ta≤70°C, VCC=15V, CT=3.3n , unless otherwise specified)
PARAMETER
STANDBY SECTION
SYMBOL
TEST CONDITION
MIN TYP MAX UNIT
Reduce Frequency Point of Standby Mode
REFERENCE SECTION
Reference Output Voltage
Line Regulation
VCOMP
Right load
2.2
V
VREF
∆VREF
∆VREF
ISC
IOUT=1.0mA
4.95
5.0 5.05
V
12V≤VCC≤25V
IOUT=1.0mA to 20mA
3
8
20
25
mV
mV
mA
Load Regulation
Output Short Circuit Current
OSCILLATOR SECTION
Frequency
-30
49
-65 -180
fOSC1
fOSC2
Normal
52
14
55
KHz
KHz
％
Frequency
No load or right load
Frequency Change
∆fOSC/∆V 12V≤VCC≤25V
0.2
1.6
1.2
2.8
1.0
VOSC(P-P)
VOSCL
V
V
V
Oscillator Voltage
VOSCH
ERROR AMPLIFIER SECTION
Input Voltage
VI(EA)
VCOMP=2.5V
2.42 2.50 2.58
V
µA
dB
MHz
dB
mA
mA
V
Input Bias Current
AVOL
II(BIAS)
VFB=5V
-0.3
90
1
-2
2V≤VOUT≤4V
60
0.7
60
Unity Gain Bandwidth
PSRR
TJ=25°C(Note1)
12V≤VCC≤25V
VFB=2.7V, VCOMP=1.1V
70
4
Output Sink Current
Output Source Current
VOUT High
ISINK
2
ISOURCE VFB=2.3V, VCOMP=5V
-0.5
5.0
-0.7
5.6
0.8
VOH
VOL
VFB=2.3V, RL=15K to GND
VFB=2.7V, RL=15K to VREF
VOUT Low
1.1
V
CURRENT SENSE SECTION
Gain
GV
(Note2,3)
2.85
0.9
3
1
3.15
1.1
V/V
V
Maximum Input Signal
PSRR
VI(MAX)
VCOMP=5V(Note2)
12V≤VCC≤25V
70
-2
dB
µA
nS
Input Bias Current
Delay to Output
IBIAS
-10
150 300
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UC3842G
LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS (Cont.)
PARAMETER
SYMBOL
TEST CONDITION
MIN
TYP MAX UNIT
OUTPUT SECTION
Output Voltage With UVLO Active
VOL(UVLO) VCC=6V,ISINK=1mA
0.8
0.1
1.1
0.4
2.2
V
V
V
V
V
ISINK=20mA
VOL
ISINK=200mA
1.6
Output Voltage
ISOURCE=20mA
VOH
13
12
14.5
14.6
100
100
ISOURCE=200mA
tR
tF
CL=1.0nF(Note1)
CL=1.0nF(Note1)
150
150
Output Voltage Rise and Fall time
nS
UNDER VOLTAGE LOCKOUT SECTION
Startup Threshold
VTH(STAR-UP)
13.5
8.5
15
10
16.5
11.5
V
V
Min Operating Voltage
PWM SECTION
VOPR(MIN) After Turn-ON
Max Duty Cycle
DMAX
DMIN
92
30
94
%
%
Minimum Duty Cycle
0
TOTAL DEVICE
Power Supply Zener Voltage
Power Operating Supply Current
Startup Current
VZ
ICC=25mA
Note2
39
7
V
ICC
10
mA
µA
ISTART-UP VCC=14V,UVLO Active
150
300
Note: 1.These parameters, although guaranteed, are not 100% tested in production.
2.Parameters measured at trip point of latch with VFB=0.
3.Gain defined as: A=ΔVCOMP/ΔVCS; 0≤VCS≤0.8V
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UC3842G
LINEAR INTEGRATED CIRCUIT
OPEN-LOOP TEST CIRCUIT
VCOMP
COMP
FB
VREF
1
8
Rb
100k
10p
Ra
100k
VIN
or
VCC
2
3
4
7
6
5
CIN
VFB
470μ
VCC
Vpwl
CS
Output
GND
5K
adjust
CT
CT
3.3n
High peak current associated with capacity loads necessitate careful grounding techniques. Timing and bypass
capacitors should be connected close to pin5 in single point GND.
UNDER-VOLTAGE LOCKOUT
During Under-Voltage Lockout, the output driver is biased to a high impedance state. Pin6 should be shunt to
GND with a bleeder resistor to prevent activing the power switch with output leakage currents.
ERROR AMPLIFIER CONFIGURATION
Error amplifier can source or sink up to 0.5mA
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UC3842G
LINEAR INTEGRATED CIRCUIT
CURRENT SENSE CIRCUIT
Error Amplifier
2R
Is
R
1V
1
3
5
Current Sense Comparator
R
Rs
C
Peak current (IS) determined by the formula: ISMAX=1V/Rs. A small RC filter be required to suppress switch
transients
OSCILLATOR AND STANDBY MODE
We can judge the state of output load through the voltage of PIN1. In order to reduce the standby power, it will
reduce the OSC frequency at right load. When VCOMP≤2.2V, the OSC frequency begins to reduce. The normal
frequency is 52KHz, the minimum frequency is 14KHz.
VCOMP
2.2V
Increase
1.2V
Standby mode
Normal
Normal
Minimum frequency :14KHz
Frequency: 52KHz
Frequency: 52KHz
OSC triangle wave
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UC3842G
LINEAR INTEGRATED CIRCUIT
SHUTDOWN TECHNIQUE
1kΩ
1
8
3
Shutdown
Shutdown
To current
Sense resistor
Shutdown UTC UC3842G can be accomplished by two methods; either raise pin 3 above 1V or pull Pin 1
below a voltage two diode drops above ground.
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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